Association between sleep duration and a new onset of nonalcoholic fatty liver disease.

Objective A short sleep duration is associated with non-alcoholic fatty liver disease (NAFLD). However, the causal relationship between a short sleep duration and the onset of NAFLD remains unknown because of the lack of any longitudinal studies. Therefore, we evaluated the association between sleep duration and the onset of NAFLD. Methods We evaluated health checkup data for 1,862 NAFLD-free Japanese adults aged 33-86 years at baseline and followed those individuals for a median of 41 months. Hepatic steatosis was examined using ultrasonography (US). The Cox proportional hazards model was used to evaluate the association between sleep duration and NAFLD onset. Results Among the 1,862 participants, 483 (25.9%) developed NAFLD. The proportion of women who developed NAFLD was the highest in the group with a sleep duration of <6 hours and lowest in the group with a sleep duration of 7 to <8 hours. The multivariable-adjusted hazard ratio (95% confidence interval) for the onset of NAFLD in women with a sleep duration <6 hours compared with those with a sleep duration of 7 to <8 hours was 1.55 (1.09-2.20; p=0.02). Conclusions In women, a short sleep duration was independently associated with the onset of NAFLD, thus suggesting that an adequate sleep duration can be a promising preventive factor for the onset of NAFLD in women.